The drift speed in a copper wire is 7.89 ✕ 10−5 m/s for a typical electron current. calculate the magnitude of the electric field e inside the copper wire. the mobility of mobile electrons in copper is 4.5 ✕ 10−3 (m/s)/(n/c). (note that though the electric field in the wire is very small, it is adequate to push a sizable electron current through the copper wire.)